The Hawks have been at their best when Collins plays alongside Josh Smith and Al Horford (again, we're talking about just 141 offensive and 140 defensive possessions here) but the Hawks have still been well on the plus side of things during the other 117 offensive and 113 defensive possessions Collins has been on the floor:

Combination

Off Eff

Def Eff

Diff

Poss

Smith & Horford & Collins

110.6

88.6

+22.0

141

any other (incl. Collins)

107.7

89.4

+18.3

115

My suspicion is that everyone deserves credit here. Collins, for getting in shape before the season, for converting more than half of the few scoring opportunities he receives, and rebounding reasonably well by his standards, Larry Drew for spotting Collins in situations* he's most likely to succeed, and his teammates for possessing the talent to allow Collins to make use of his narrow range of ability without compromising the team's performance in general.

*Let's not forget that Collins has played more than a quarter of his minutes this season against the Magic and the Magic were without Jameer Nelson in both games. Collins might not look so good if forced to defend the pick-and-roll repeatedly. Another third of his minutes have come against New Jersey and Minnesota, teams that are -6 and -7 per 100 possessions on average, respectively.

And, should Collins remain limited to spot duty, the Hawks have another, less limited option should they want to go big: Zaza Pachulia.

Trio

Off Eff

Def Eff

Diff

Poss

Smith & Horford & Collins

110.6

88.6

+22.0

141

Smith & Horford & Pachulia

114.0

98.3

+15.7

58

I presume you're noticing a trend here: the Hawks outscoring opponents by a ton when Josh Smith plays small forward. Here are the season-to-date totals for Smith by position:

Josh Smith

Off Eff

Def Eff

Diff

Poss

at the 3

106.8

99.4

+7.4

310

at the 4

110.1

106.2

+3.9

1124

One reason these unusual lineups look so good is that there's a regular member of the rotation that is, according to the on-off data, killing the Hawks:

Josh Powell

Offense

Defense

On

Off

On

Off

2010-11

104.8

111.2

111.2

103.5

Yes, the Hawks have outscored opponents by 7.7 points per 100 possessions (over 1465 possessions) when Powell's off the court and have been outscored by their opponents by 6.4 points per 100 possessions (over 625 possessions) when Powell's on the court. Essentially, the Hawks are slightly better than the 2010-11 Orlando Magic (+7.3 points per 100 possessions) when Powell's on the bench and the 2010-11 Los Angeles Clippers (-6.4 points per 100 possessions) when Powell's on the court. Powell's season-to-date performance* might, in and of itself, be argument for more playing time for Jason Collins.